The present invention relates to the manufacture of boxes or containers out of corrugated paper or similar sheet material. More particularly, the invention relates to the manufacture of Bliss style boxes having a pair of end panels having flaps configured to define hollow corner posts and/or intermediate post reinforcements along with the end flaps and side walls of the body wrap.
A conventional Bliss box comprises a pair of rectangular end wall panels, each having marginal side and bottom areas secured to end flaps of a body wrap, the body wrap also defining the bottom and side walls of the completed box. The stacking strength of a Bliss box is superior to that of a conventional tray container but recently there have been efforts to further increase the stacking strength of the Bliss style container.
In one such attempt, each of the Bliss box end panels, prior to being brought into registration with the body wrap, has a pair of marginal flaps thereof turned inwardly to define a right angle corner post when the marginal flap is laminated, stapled or glued to the sidewall of the body wrap. In another modification, each of the end panel blanks, prior to being brought into registration with the body wrap, has a pair of marginal flaps thereof turned inwardly around a mandrel to define both a diagonal corner post and an internal marginal flap at each corner of the box when the body wrap is formed therearound on the mandrel. In another improvement, as shown in my application Ser. No. 636,917, each end panel blank is formed with an opposite end pair of flaps, each flap being subdivided into at least three areas. Each of these subdivided flaps is folded and glued to the central area of the end panel to define a hollow right triangle corner post and/or a hollow triangular intermediate post in the end wall. The completed end wall, thus preformed, is then upended and stripped from its magazine by a descending mandrel to be brought into proper registration with the Bliss body wrap to be formed therearound in the die cavity.
While machines utilizing the techniques just described have come into commercial use, the results have not been entirely satisfactory. The merely internally flanged style of Bliss box provides only a modest increase in stacking strength and does not compartmentalize the interior of the box. The Bliss box with internal flanges and diagonal corners in the end panels is an improvement in terms of stacking strength but does not compartmentalize the interior of the box and is required to be made on a machine in which the fluid cylinder for reciprocating the mandrel requires a very long stroke. The machine of my prior application results in a Bliss box having hollow corner and/or intermediate reinforcement posts and thus greatly improves the stacking strength of the box while also compartmentalizing the box. However, the mode of operation is relatively complex, involving as it does the pre-formation and gluing of the corner posts and/or intermediate posts around auxiliary mandrels prior to the feeding of the completed end panel to the machine mandrel.